CN102480223A

CN102480223A - Negative-voltage charge pump power circuit realized by low-voltage MOS (metal-oxide-semiconductor) pipe solely

Info

Publication number: CN102480223A
Application number: CN2010105584114A
Authority: CN
Inventors: 鞠建宏; 刘楠
Original assignee: DIOO MICROELECTRONIC Co Ltd
Current assignee: DIOO MICROELECTRONIC Co Ltd
Priority date: 2010-11-25
Filing date: 2010-11-25
Publication date: 2012-05-30

Abstract

The invention discloses a negative-voltage charge pump power circuit realized by low-voltage transistor solely, comprising a P-type field effect transistor, four N-type field effect transistors and two capacitors, wherein a grid of each transistor is connected with a level shift module. A source electrode of the P-type field effect transistor is connected with a substrate and then connected with a power inlet end, and a drain electrode is connected with a drain electrode of a first N-type field effect transistor. A source electrode of the first N-type field effect transistor is in short-circuit connection with the substrate to a ground potential. Drain electrodes of a second and a third N-type field effect transistors are connected to the ground potential, and the source electrodes are connected with respective substrates and then connected to a drain electrode of a fourth N-type field effect transistor. A substrate of the fourth N-type field effect transistor is in short-circuit connection with a source electrode and connected to a voltage outlet end. A first capacitor is connected with the drain electrode of the P-type field effect transistor and the source electrode of the second N-type field effect transistor. A second capacitor is connected with the source electrode of the fourth N-type field effect transistor and the ground potential. The negative-voltage charge pump power circuit of the invention realizes a negative-voltage power supply so as to reduce board area of a charge pump and enrich technical options.

Description

A kind of negative voltage charge pump power circuit that only adopts the low pressure metal-oxide-semiconductor to realize

Technical field

The present invention relates to a kind of negative voltage charge pump power circuit that only adopts the low pressure metal-oxide-semiconductor to realize.

Background technology

The negative voltage charge pump power supply has a wide range of applications in analog chip, and it can make the chip output voltage swing increase and be twice, and improves dynamic range; Can realize also that based on specific functions such as earthy signal outputs in general the requirement to the negative voltage charge pump module comprises that conversion efficiency is high, chip area is little etc.; A United States Patent (USP) (patent No. 6; 803,807) a kind of negative voltage charge pump circuit has been proposed, as shown in Figure 1; Signal S1 control switch pipe EP1 and DP1, and signal S2 control switch pipe EN1 and DP2.As switch EP1, during the DP1 conducting, C1 is recharged to Vin, and works as EN1, during the DP2 switch conduction, and C1, the C2 charge redistribution, through some all after dates, output OUT will reach-Vin.This structure can convert positive input voltage Vin to its corresponding negative output voltage OUT, but also there are some shortcomings in this structure, is example with Vin=5V:

1. DP1 and DP2 need extra consideration integrity problem in the patent.When DP1 or DP2 shutoff, its grid and underlayer voltage are 5V, and its drain potential is about-5V; Therefore need to use the stronger high voltage PMOS of voltage endurance capability to bear this grid-leakage, the 10V voltage difference of substrate-leakage, the use of high tension apparatus has limited the selection of technology on the one hand; On the other hand, because the influence of high tension apparatus grid oxygen specific capacitance and threshold voltage makes to reach identical charges pump driving force; DP1, DP2 must use bigger chip area.

2. the substrate electric potential of DP1 and DP2 all is connected to positive potential in the patent, Vin, and this makes these two PMOS have serious substrate bias effect; Reduce its current driving ability; Therefore want to guarantee identical charge pump performance, must strengthen DP1, the chip area of DP2.

In the patent in order to transmit 0V and-5V (B point current potential), DP1 and DP2 have selected the PMOS of depletion type, though this can realize effectively that low-voltage transmits, the use of particular device has also limited the selection of technology.

Summary of the invention

Because the problems referred to above that prior art exists the objective of the invention is to propose a kind of negative voltage charge pump power circuit that only adopts the low pressure metal-oxide-semiconductor to realize, it can effectively solve the problem that prior art exists.

For realizing above-mentioned purpose; A kind of negative voltage charge pump power circuit that only adopts low voltage transistor to realize that the present invention proposes; Comprise a p type field effect transistor, four n type field effect transistors and two electric capacity, wherein each transistorized grid is connected with a level shift module; The source electrode of p type field effect transistor be connected in power input after substrate links to each other, and its drain electrode links to each other with the drain electrode of first n type field effect transistor; The source electrode of first n type field effect transistor be connected to earth potential after its substrate links to each other; The drain electrode of second, third n type field effect transistor all is connected to earth potential, and its source electrode and the drain electrode that is connected in the 4th n type field effect transistor after its substrate separately links to each other; The source electrode of the 4th n type field effect transistor be connected to voltage output end after its substrate links to each other; The two ends of first electric capacity are connected to the drain electrode of p type field effect transistor and the source electrode of second n type field effect transistor; The two ends of second electric capacity are connected respectively to the source electrode and the earth potential of the 4th n type field effect transistor.

As further characteristic of the present invention, each transistor is a low-voltage tube.

Owing to adopted above technical scheme, the present invention only to adopt common low voltage transistor device just can realize negative voltage power supply, reduce the chip area of charge pump, and enriched the selection of technology, can effectively solve the problem that prior art exists.

Description of drawings

Fig. 1 is a United States Patent (USP) 6,803, the negative voltage charge pump circuit diagram that proposes in 807;

Fig. 2 is a negative voltage charge pump power circuit sketch map of the present invention;

N type field effect transistor (NM2A, NM2B, NM3) sketch map of Fig. 3 for isolating among the present invention;

Among the figure:

The N+:N type injects

The P+:P type injects

NWELL:N type well region

Psub:P type substrate

NBL:N type buried regions zone

D, S, G, the drain terminal of B:N type field-effect transistor, source end, grid end and substrate terminal

VCC: supply voltage

Fig. 4 is the generation circuit diagram of Vc among the present invention;

Fig. 5 is level shift circuit sketch map among the present invention.

Embodiment

According to accompanying drawing and specific embodiment the present invention is described further below:

As shown in Figure 2; A kind of negative voltage charge pump power circuit that only adopts low voltage transistor to realize that the present invention proposes; Comprise a p type field effect transistor PM1, four n type field effect transistor NM1, NM2, NM3, NM4 and two capacitor C 1, C2, wherein each transistorized grid is connected with a level shift module (Level Shift Block); The source electrode of p type field effect transistor PM1 be connected in power input Vin after substrate links to each other, and its drain electrode links to each other with the drain electrode of the first n type field effect transistor NM1; The source electrode of the first n type field effect transistor NM1 be connected to earth potential after its substrate links to each other; The drain electrode of second, third n type field effect transistor NM2, NM3 all is connected to earth potential, and its source electrode and the drain electrode that is connected in the 4th n type field effect transistor NM4 after its substrate separately links to each other; The source electrode of the 4th n type field effect transistor NM4 be connected to voltage output end Vout after its substrate links to each other; The two ends of first capacitor C 1 are connected to the drain electrode of p type field effect transistor PM1 and the source electrode of second and third n type field effect transistor NM2; The two ends of second capacitor C 2 are connected respectively to source electrode and the earth potential of the 4th n type field effect transistor NM4.

In the present embodiment; The p type field effect transistor PM1 and the first n type field effect transistor NM1 grid voltage are that 0V is to power source voltage Vcc; The level shift module that is added (level shift block) is merely Postponement module, in order on sequential, to be consistent with other switch; The grid control signal of the second n type field effect transistor NM2 is VN～VP, and when this switch conduction, its grid voltage is VP, is example with VCC=5V, VP=5V, and 0V is to the N point in second n type field effect transistor NM2 transmission this moment; When this switch turn-offs; The grid voltage of the second n type field effect transistor NM2 is VN; And this moment the first n type field effect transistor NM1; The 4th n type field effect transistor NM4 conducting, VN point voltage be-5V, therefore the second n type field effect transistor NM2 effectively cut off 0V and its source end of its drain terminal-5V; The grid-control voltage of the 4th n type field effect transistor NM4 is selected Vout～Vout+Vc, and Vc need select according to the reliability requirement of employing device, in the present invention, and Vc=5V.When the 4th n type field effect transistor NM4 conducting, its source end and drain terminal voltage are equal basically, i.e. Vout=VN=-5V, and this moment, its grid voltage was 0V, therefore can effectively transmit-and 5V to Vout holds; When the 4th n type field effect transistor NM4 turn-offs, Vout=-5V, VN=0V, this moment, its grid voltage was-5V, effectively voltage is leaked in the partition source.The introducing of the 3rd n type field effect transistor NM3 is in order to improve electric charge pump performance when starting.In initial start stage, N point and P point voltage are 0V, and this makes that the control signal amplitude of variation at this stage second n type field effect transistor NM2 grid is 0V; Therefore can't normally open, thereby charge pump can't normally start, the grid voltage excursion of the 3rd n type field effect transistor NM3 is Vout～Vout+Vc; The startup stage; Even Vout=0V, but the grid high voltage of the 3rd n type field effect transistor NM3 is Vout+Vc, i.e. 5V; This makes the 3rd n type field effect transistor NM3 effectively to open, and 0V is delivered to the N point.And in normal work stage; As the first p type field effect transistor PM1, during the second n type field effect transistor NM2 conducting, the grid potential that is added in the 3rd n type field effect transistor NM3 is Vout+Vc; Be OV; N point current potential also is 0V, and therefore the 3rd n type field effect transistor NM3 is an off state, mainly by the second n type field effect transistor NM2 0V is delivered to the N point; As the first p type field effect transistor PM1, when the second n type field effect transistor NM2 turn-offed, the grid potential that is added in the 3rd n type field effect transistor NM3 was Vout, promptly-5V, therefore this moment, the 3rd n type field effect transistor NM3 still was an off state.So the 3rd n type field effect transistor NM3 only works in initial start stage, under normal condition, it keeps off state always.Through above-mentioned analysis, all switching tubes, under the arbitrary operational state, grid, the source, mutual potential difference does not all have beyond supply voltage between leakage and the substrate, and therefore VCC just integrity problem can not occur yet.

In the present embodiment, each transistor is low-voltage tube (as shown in Figure 3), and effective like this this circuit that guaranteed has minimum chip area.Owing to adopted the low voltage transistor switch, grid-control voltage that therefore must be different according to the different working state design is with normal transmission that guarantees negative voltage and the appearance of avoiding integrity problem; Use the NBL layer with second, third n type field effect transistor that is designed to isolate with the 4th n type field effect transistor NM2, NM3, NM4; Make each transistorized substrate electric potential independent, and link to each other, can avoid substrate bias effect, reduce the wide long size of switching tube with source electrode separately.

In the present embodiment; As shown in Figure 2, switch P M1, NM1, NM2, NM3, the wide long size of NM4 will be according to the load sizes of charge pump, switch control clock frequency; Capacitor C 1; The selection of compromising of the appearance value of C2, because NM3 only works and be in off state in normal operation in initial start stage, so its breadth length ratio can be chosen slightly smaller to save area.Capacitor C 1, C2 is generally the outer electric capacity of sheet, and its appearance value is chosen according to chip application, all selects 1uF. Vout+Vc to be produced by circuit shown in Figure 4 here, through choose reasonable Ibias and R1, can obtain Vc=5V easily.The output level of controlling the level shift circuit of all switch gate voltages has nothing in common with each other, but this body structure of level shift circuit is identical, and is as shown in Figure 5; This shift circuit adopts two-stage displacement scheme; At first incoming level scope GND～VCC is adjusted to VL～VCC, again VL～VCC is adjusted to VL～VH, and as final output level; Therefore only need choose reasonable VH, VL can obtain different grid-control voltages.

But above-mentioned embodiment is exemplary, is to be the restriction that this patent is comprised scope in order better to make those skilled in the art can understand this patent, can not to be interpreted as; So long as according to spirit that this patent discloses done anyly be equal to change or modify, all fall into the scope that this patent comprises.

Claims

1. negative voltage charge pump power circuit that only adopts low voltage transistor to realize, it is characterized in that: comprise a p type field effect transistor, four n type field effect transistors and two electric capacity, wherein each said transistorized grid is connected with a level shift module; Be connected in power input after the substrate of the source electrode and its of described p type field effect transistor oneself links to each other, and its drain electrode links to each other with the drain electrode of first n type field effect transistor; The source electrode of said first n type field effect transistor and its substrate are connected earth potential after linking to each other; The drain electrode of said second, third n type field effect transistor all is connected to earth potential, and its source electrode and the drain electrode that is connected in said the 4th n type field effect transistor after its substrate separately links to each other; The source electrode of said the 4th n type field effect transistor be connected to voltage output end after its substrate links to each other; The two ends of said first electric capacity are connected to the drain electrode of p type field effect transistor and the source electrode of said second and third n type field effect transistor; The two ends of said second electric capacity are connected respectively to the source electrode and the earth potential of said the 4th n type field effect transistor.

2. the negative voltage charge pump power circuit that only adopts low voltage transistor to realize according to claim 1, it is characterized in that: described each transistor is a low-voltage tube.